| Acronym | Meaning |
| DELPHI | Detector With Lepton |
| DEM | Digital Elevation Model |
| DEM | Discrete Element Method |
| DEM | Distinguishable Electron Method |
| DEMA | Diesel Engine Manufacturers Association |
| DEMA | Distributed Electromechanical Actuator |
| DEMS | Differential Electrochemical Mass Spectrometry |
| DENIS | Deep Near-Infrared Survey |
| DENT | Double-edge Notched Tension |
| DEP | Department Of Environmental Protection |
| DEP | Diethyl Phthalate |
| DEPC | Diethyl Pyrocarbonate |
| DEPT | Distortionless Enhancement By Polarization Transfer |
| DEQ | Department Of Environmental Quality |
| DERA | Defense Environmental Restoration Act |
| DERP | Defense Environmental Restoration Program |
| DESPOT | Driven-equilibrium Single-pulse Observation Of T1 |
| DESY | Deutsches Elektronen-Synchrotron |
| DET | Direct Nonradiative Electronic Energy Transfer |
| DETA | Dielectric Thermal Analysis |
| DETOCSY | Diffusion Edited Total Correlation Spectroscopy |
| DEXA | Dual Energy X-ray Absorptiometry |
| DEXAFS | Dispersive Extended X-ray Absorption Fine Structure |
| DF | Decontamination Factor |
| DF | Density Functional Formalism |
| DF-OCE | Dirac-Fock One-center Expansion |
| DF-SCF | Dirac-Fock Self-consistent Field |
| DFA | Detrended Fluctuation Analysispar |
| DFA | Discriminant Function Analysispar |
| DFA | Discontinuous Flow Analysis |
| DFA | Dual Fouling Apparatus |
| DFAA | Dissolved Free Amino Acids |
| DFB | Diffusion Brazing |
| DFB | Distributed Feedback |
| DFDL | Distributed-feedback Dye Laser |
| DFFT | Double Forward Fourier Transformation |
| DFG | Difference Frequency Generation |
| DFM | Dark Field Microscopy |
| DFM | Dynamic Force Microscopy |
| DFMFT | Density-functional Mean-field Theory |
| DFP | Diisopropyl Fluorophosphate |
| DFPT | Density-functional Perturbation Theory |
| DFS | Daily Flow System (file Within STORET) |
| DFS | Disease Free Survival |
| DFT | Density-functional Theory |
| DFTG | Density Functional Theory (with) Gradient (corrections) |
| DFTS | Dispersive Fourier Transform Spectrometry |
| DFW | Diffusion Welding |
| DFWM | Degenerate Four-wave Mixing |
| DFZ | Dislocation Free Zone |